Lignin catalytic hydroconversion in a semi-continuous reactor: an experimental study

International audienceThe valorization of lignin coming from pulp industry or bio-ethanol refineries into renewable chemicals is one of the great challenges of the biorefinery concept. Among the several processes proposed to depolymerize lignin, catalytic hydroconversion appeared efficient to get high liquid yield and can provide targeted aromatic monomers. A new semi-continuous set-up consisting in a batch reactor opened on the gas-phase was implemented to carry out the catalytic lignin liquefaction into phenolic and deoxygenated aromatic compounds with continuous H2 feeding. The interest of this equipment is the continuous removing of light products and water from the reacting mixture whereas the hydrogen donor solvent is reintroduced in the reactor via a reflux/condensing system. A Co-promoted Mo sulfide catalyst was used and thanks to efficient separation and extensive analysis, the components of the different gaseous, liquid and solid fractions obtained were identified and quantified. The evolution of the various fractions in function of the time and the deep investigation of the composition, allowed to propose a reaction scheme for the lignin depolymerization in those operating conditions